Magnitude and frequency variations of vector-borne infection outbreaks using the Ross-Macdonald model: explaining and predicting outbreaks of dengue fever.

The classical Ross-Macdonald model is often utilized to model vector-borne infections; however, this model fails on several fronts. First, using measured (or estimated) parameters, which values are accepted from the literature, the model predicts a much greater number of cases than what is usually observed. Second, the model predicts a single large outbreak that is followed by decades of much smaller outbreaks, which is not consistent with what is observed. Usually towns or cities report a number of recurrences for many years, even when environmental changes cannot explain the disappearance of the infection between the peaks. In this paper, we continue to examine the pitfalls in modelling this class of infections, and explain that, if properly used, the Ross-Macdonald model works and can be used to understand the patterns of epidemics and even, to some extent, be used to make predictions. We model several outbreaks of dengue fever and show that the variable pattern of yearly recurrence (or its absence) can be understood and explained by a simple Ross-Macdonald model modified to take into account human movement across a range of neighbourhoods within a city. In addition, we analyse the effect of seasonal variations in the parameters that determine the number, longevity and biting behaviour of mosquitoes. Based on the size of the first outbreak, we show that it is possible to estimate the proportion of the remaining susceptible individuals and to predict the likelihood and magnitude of the eventual subsequent outbreaks. This approach is described based on actual dengue outbreaks with different recurrence patterns from some Brazilian regions.

Defining priorities for dog population management through mathematical modeling.

We simulated dog population dynamics for a thirty-years period using a logistic growth model. Through sensitivity analyses, we determined the influence of the parameters used in the model. Carrying capacity was the most influential parameter in all simulations. In the owned-dog population, the influence of immigration, abandonment and births was 19%, 16% and 6% of the influence of the carrying capacity, respectively. In the sterilized owned-dog population, the influence of abandonment, female and male sterilization was 37%, 30% and 27% of the influence of the carrying capacity. In the stray population, the influence of abandonment, carrying capacity of the owned-dog population and adoption was 10%, 9% and 6% of the influence of the carrying capacity. In the sterilized stray population, the influence of births, female sterilization and male sterilization was 45%, 15% and 13% of the influence of the carrying capacity. Other parameters had lower influence values. Modification of the carrying capacity requires different interventions for the owned- and stray-dog populations. Dog trade control is a way to reduce immigration. The evaluation of sterilization effects must focus on the variations in the infertile population fraction. Adoption may improve the effects of the reduction in carrying capacity on the stray-dog population.

Economic analysis of vaccination to control bovine brucellosis in the States of Sao Paulo and Mato Grosso, Brazil.

Brucellosis is a zoonotic disease that causes important economic losses in Brazil, and the country has therefore established a national program for its control and eradication. Using data generated in the last national brucellosis survey, we conducted an economic analysis in two Brazilian States with different brucellosis status, Mato Grosso (with high prevalence) and Sao Paulo (with low prevalence). The economic analysis was based on the calculation of the additional benefits and costs of controlling bovine brucellosis through the vaccination of heifers aged between 3 and 8 months with S19 vaccine, considering maximal and minimal impacts of the disease. The analysis showed that vaccinating 90% of the replacement heifers aged 3-8 months of age offers the best economic performance in a vaccination program against bovine brucellosis if compared to vaccination rates of 70% and 80%. Moreover, regions with higher prevalences of bovine brucellosis would experience significant economic advantages when implementing a vaccination strategy to control the disease. This economic analysis will allow decision makers to plan more economically effective vaccination programs.

Interpretations and pitfalls in modelling vector-transmitted infections.

In this paper we propose a debate on the role of mathematical models in evaluating control strategies for vector-borne infections. Mathematical models must have their complexity adjusted to their goals, and we have basically two classes of models. At one extreme we have models that are intended to check if our intuition about why a certain phenomenon occurs is correct. At the other extreme, we have models whose goals are to predict future outcomes. These models are necessarily very complex. There are models in between these classes. Here we examine two models, one of each class and study the possible pitfalls that may be incurred. We begin by showing how to simplify the description of a complicated model for a vector-borne infection. Next, we examine one example found in a recent paper that illustrates the dangers of basing control strategies on models without considering their limitations. The model in this paper is of the second class. Following this, we review an interesting paper (a model of the first class) that contains some biological assumptions that are inappropriate for dengue but may apply to other vector-borne infections. In conclusion, we list some misgivings about modelling presented in this paper for debate.

Detecting livestock production zones.

Communities are sets of nodes that are related in an important way, most likely sharing common properties and/or playing similar roles within a network. Unraveling a network structure, and hence the trade preferences and pathways, could be useful to a researcher or a decision maker. We implemented a community detection algorithm to find livestock communities, which is consistent with the definition of a livestock production zone, assuming that a community is a group of farm premises in which an animal is more likely to stay during its lifetime than expected by chance. We applied this algorithm to the network of animal movements within the state of Mato Grosso for 2007. This database holds information concerning 87,899 premises and 521,431 movements throughout the year, totaling 15,844,779 animals moved. The community detection algorithm achieved a network partition that shows a clear geographical and commercial pattern, two crucial features for preventive veterinary medicine applications; this algorithm provides also a meaningful interpretation to trade networks where links emerge based on trader node choices.

Prevalence and risk-mapping of bovine brucellosis in Maranhão State, Brazil.

Between 2007 and 2009, a cross-sectional survey was carried out in Maranhão State, Brazil to estimate the seroprevalence of and risk factors for bovine brucellosis. In total, 749 herds and 6779 cows greater than two years of age were blood sampled. At the time of sampling a questionnaire to collect details on possible risk factors for bovine brucellosis was administered to the participating herd manager. A logistic regression model was developed to quantify the association between herd demographic and management characteristics and the herd-level brucellosis status. Spatial analyses were carried out to identify areas of the state where the presence of brucellosis was unaccounted-for by the explanatory variables in the logistic regression model. The estimated herd-level prevalence of brucellosis in Maranhão was 11.4% (95% CI 9.2-14) and the individual animal-level prevalence was 2.5% (95% CI 1.7-3.6). Herds with more than 54 cows older than two years of age, herds that used rented pasture to feed cattle, and the presence of wetlands on the home farm increased the risk of a herd being brucellosis positive. Infected farms were identified throughout the state, particularly in the central region and on the northwestern border. Spatial analyses of the Pearson residuals from the logistic regression model identified an area in the center of the state where brucellosis risk was not well explained by the predictors included in the final logistic regression model. Targeted investigations should be carried out in this area to determine more precisely the reasons for the unexplained disease excess. This process might uncover previously unrecognized risk factors for brucellosis in Maranhão.

Modelling immunization strategies with cytomegalovirus vaccine candidates.

In order to analyse the impact of vaccination against cytomegalovirus (CMV) on congenital infection incidence using current vaccines tested in phase II clinical trials, we simulated different scenarios by mathematical modelling, departing from the current vaccine characteristics, varying age at vaccination, immunity waning, vaccine efficacy and mixing patterns. Our results indicated that the optimal age for a single vaccination interval is from 2 to 6 months if there is no immunity waning. Congenital infection may increase if vaccine-induced immunity wanes before 20 years. Congenital disease should increase further when the mixing pattern includes transmission among children with a short duration of protection vaccine. Thus, the best vaccination strategy is a combined schedule: before age 1 year plus a second dose at 10-11 years. For CMV vaccines with low efficacy, such as the current ones, universal vaccination against CMV should be considered for infants and teenagers.

Avaliação de testes sorológicos de triagem para diagnóstico da brucelose bubalina / Evaluation of screening serological tests for brucellosis diagnosis in buffaloes

The study compared the performance of three screening serological tests: buffered plate antigen (BPA), Rose-Bengal produced with 1119-3 Brucella abortus strain (RB1119-3), and Rose-Bengal produced with 99 Brucella abortus strain (RB99). Sera from 696 adult female animals were submitted to BPA, RB1119-3, RB99, 2-mercaptoethanol test (ME), and complement fixation test (FC). The gold standard was the combination of CF and ME. The Kappa values for BPA, RB99, and RB1119-3 were 0.82, 0.74, and 0.70, respectively. The relative sensitivity and specificity for the same tests were 0.98 and 0.96, 0.92 and 0.94, and 0.95 and 0.92, respectively. These results indicate that BPA is a better screening test than RB for buffalo, regardless of the B. abortus strain in RB.

Estimation of R0 from the initial phase of an outbreak of a vector-borne infection.

The magnitude of the basic reproduction ratio R(0) of an epidemic can be estimated in several ways, namely, from the final size of the epidemic, from the average age at first infection, or from the initial growth phase of the outbreak. In this paper, we discuss this last method for estimating R(0) for vector-borne infections. Implicit in these models is the assumption that there is an exponential phase of the outbreaks, which implies that in all cases R(0)>1. We demonstrate that an outbreak is possible, even in cases where R(0) is less than one, provided that the vector-to-human component of R(0) is greater than one and that a certain number of infected vectors are introduced into the affected population. This theory is applied to two real epidemiological dengue situations in the southeastern part of Brazil, one where R(0) is less than one, and other one where R(0) is greater than one. In both cases, the model mirrors the real situations with reasonable accuracy.

Situação epidemiológica da brucelose bovina no Estado da Bahia / Epidemiological situation of bovine brucellosis in the State of Bahia, Brazil

O trabalho consistiu em estratificar o Estado da Bahia em quatro regiões com características homogêneas (circuitos produtores) para que fossem amostradas aleatoriamente, em cada uma delas, 300 propriedades. Em cada propriedade foram escolhidas, de forma aleatória, 10 a 15 fêmeas bovinas adultas, das quais foi obtida uma amostra de sangue. No total, foram amostrados 10.816 animais, provenientes de 1.413 propriedades. O protocolo de testes utilizado foi o da triagem com o teste do antígeno acidificado tamponado (Rosa Bengala) e a confirmação dos positivos com o teste do 2-mercaptoetanol. O rebanho foi considerado positivo se pelo menos um animal reagiu às duas provas sorológicas. As prevalências de focos e a de fêmeas adultas soropositivas do Estado foram de 4,2 por cento [3,1-5,3 por cento] e 0,66 por cento [0,41-0,93 por cento], respectivamente. Para os circuitos produtores foram: circuito 1, 5,8 por cento [3,6-8,7 por cento] e 0,86 por cento [0,41-1,3 por cento]; circuito 2, 3,1 por cento [1,5-5,6 por cento] e 1,2 por cento [0,25-2,1 por cento]; circuito 3, 6,3 por cento [4,0-9,3 por cento] e 1,7 por cento [0,66-2,7 por cento]; e circuito 4, 0,60 por cento [0,07-2,2 por cento] e 0,07 [0,00-0,21 por cento]. Para a análise de fatores de riscos associados à doença foi aplicado um questionário epidemiológico em cada propriedade visitada. Os fatores de risco (odds ratio, OR) associados à condição de foco foram: compra de reprodutores (OR= 2,27) e presença de áreas alagadiças (OR= 1,76). A vacinação de fêmeas de três até oito meses de idade foi um fator de proteção (OR= 0,53).

A study to characterize the epidemiological situation of bovine brucellosis in the State of Bahia was carried out in 2004. The State was divided into four similar production regions, 300 herds were randomly sampled in each region, and 10 to 15 adult bovine females were sampled in each of these herds. A total of 10,816 serum samples from 1,413 herds were collected. The serum samples were screened for antibodies to Brucella spp. by the Rose-Bengal Test (RBT), and all RBT-positive sera were re-tested by the 2-mercaptoethanol test (2-ME) for confirmation. A herd was considered positive if at least one animal was positive on both RBT and 2-ME tests. The prevalence of infected herds and seropositive adult bovine females in Bahia State were: 4.2 percent [3.1-5.3 percent] and 0.66 percent [0.41-0.93 percent], respectively. In the production regions, prevalence of infected herds and animals were, respectively: region 1, 5.8 percent [3.6-8.7 percent] and 0.86 percent [0.41-1.3 percent]; region 2, 3.1 percent [1.5-5.6 percent] and 1.2 percent [0.25-2.1 percent]; region 3, 6.3 percent [4.0-9.3 percent] and 1.7 percent [0.66-2.7 percent]; and region 4, 0.60 percent [0.07-2.2 percent] and 0.07 percent[0.00-0.2 percent]. In each herd, an epidemiological questionnaire was applied. The risk factors (odds ratio, OR) associated with the presence of the infection were: purchase of breeding animals (OR = 2.27) and presence of flood areas (OR= 1.76). Vaccination of heifers from three to eight months of age was a protective factor (OR=0.53).

Situação epidemiológica da brucelose bovina no Distrito Federal / Epidemiological status of bovine brucellosis in the Federal District, Brazil

Realizou-se um estudo para caracterizar a situação epidemiológica da brucelose bovina no Distrito Federal (DF). No total foram amostrados 2.019 animais, provenientes de 278 propriedades. Em cada propriedade visitada aplicou-se um questionário epidemiológico para verificar o tipo de exploração e as práticas de criação e sanitárias que poderiam estar associadas ao risco de infecção pela doença. O protocolo utilizado foi o da triagem com o teste do antígeno acidificado tamponado e a confirmação dos positivos com o teste do 2-mercaptoetanol. O rebanho foi considerado positivo quando pelo menos um animal foi reagente às duas provas sorológicas. A prevalência no DF foi de 2,5 por cento [1,0-5,1 por cento] para propriedades e de 0,16 por cento [0,04-0,28 por cento] para animais. Em razão dos resultados encontrados, que permitem pensar em estratégias de erradicação, recomenda-se que o DF intensifique o diagnóstico de brucelose, tanto na forma de testes sorológicos sistemáticos como pela introdução de mecanismos de detecção rápida em laticínios, em ambos os casos a fim de aumentar o número de propriedades certificadas como livres da doença e melhorar a sensibilidade do sistema de vigilância ativa.

A study to characterize the epidemiological status of brucellosis was carried out in the Federal District of Brazil. A total of 2,019 serum samples from 278 herds were collected. In each herd, it was applied an epidemiological questionnaire focused on herd traits as well as husbandry and sanitary practices that could be associated with the risk of infection. The serum samples were screened for antibodies against Brucella spp. by the Rose-Bengal Test (RBT), and all positive sera were re-tested by the 2-mercaptoethanol test (2-ME). The herd was considered positive if at least one animal was positive on both RBT and 2-ME tests. Herd prevalence was estimated as 2.5 percent [1.0-5.1 percent] whereas animal prevalence was 0.16 percent [0.04-0.28 percent]. Given these results, that may warrant the implementation of eradication strategies, there is a case for intensifying the serological testing in the Federal District, coupled with the introduction of rapid detection methods by the dairy industries, with a view to increasing the number of accredited free herds and improving the sensitivity of the surveillance system..

Situação epidemiológica da brucelose bovina no Estado do Espírito Santo / Epidemiological situation of bovine brucellosis in the State of Espírito Santo, Brazil

Realizou-se um estudo para caracterizar a situação epidemiológica da brucelose bovina no Estado do Espírito Santo. O Estado foi dividido em dois circuitos produtores. Em cada circuito foram amostradas aleatoriamente cerca de 300 propriedades e, dentro dessas, foi escolhido de forma aleatória um número pré-estabelecido de animais, dos quais foi obtida uma amostra de sangue. No total, foram amostrados 5.351 animais, provenientes de 622 propriedades. Em cada propriedade amostrada foi aplicado um questionário epidemiológico para verificar o tipo de exploração e as práticas de criação e sanitárias que poderiam estar associadas ao risco de infecção pela doença. O protocolo de testes utilizado foi o da triagem com o teste do antígeno acidificado tamponado e o reteste dos positivos com o teste do 2-mercaptoetanol. O rebanho foi considerado positivo quando pelo menos um animal foi reagente às duas provas sorológicas. Para o Estado, as prevalências de focos e de animais infectados foram, respectivamente, de 9,0 por cento [7,0-11,6 por cento] e 3,5 por cento [1,9-6,4 por cento]. Para os circuitos, as prevalências de focos e de animais infectados foram, respectivamente, de: circuito 1, 6,8 por cento [4,5-10,2 por cento] e 3,4 por cento [1,3-8,6 por cento]; circuito 2, 10,9 por cento [7,9 por cento-14,8 por cento] e 3,7 por cento [2,1-6,3 por cento]. Os fatores de risco (odds ratio, OR) associados à condição de foco foram: utilização de inseminação artificial (OR = 7,05 [2,51-19,82]) e confinamento/semiconfinamento dos animais (OR = 2,98 [1,22-7,26]). A vacinação de fêmeas entre três e oito meses de idade foi um fator protetor (OR = 0,03 [0,01-0,1]).

A study to characterize the epidemiological status of brucellosis was carried out in the State of Espírito Santo. The State was divided in two regions. Three hundred herds were randomly sampled in each region and a pre-established number of animals were sampled in each of these herds. A total of 5,351 serum samples from 622 herds were collected. In each herd, it was applied an epidemiological questionnaire focused on herd traits as well as husbandry and sanitary practices that could be associated with the risk of infection. The serum samples were screened for antibodies against Brucella spp. by the Rose-Bengal Test (RBT), and all positive sera were re-tested by the 2-mercaptoethanol test (2-ME). The herd was considered positive if at least one animal was positive on both RBT and 2-ME tests. The prevalence of infected herds and animals in the State were, respectively, 9.0 percent [7.0-11.6 percent] and 3.5 percent [1.9-6.4 percent]. The prevalence of infected herds and animals in the regions were, respectively: region 1, 6.8 percent [4.5-10.2 percent] and 3.4 percent [1.3-8.6 percent]; and region 2, 10.9 percent [7.9-14.8 percent] and 3.7 percent [2.1-6.3 percent]. The risk factors (odds ratio, OR) associated with the presence of the infection were: use of artificial insemination (OR = 7.05 [2.51-19.82]) and intensive/semi-intensive management systems (OR = 2.98 [1.22-7.26]). Vaccination of heifers from three to eight months of age was a protective factor (OR = 0.03 [0.01-0.1]).

Situação epidemiológica da brucelose bovina no Estado de Goiás / Epidemiological status of bovine brucellosis in the State of Goiás, Brazil

Realizou-se um estudo para caracterizar a situação epidemiológica da brucelose no Estado de Goiás. O Estado foi estratificado em três circuitos produtores. Em cada circuito foram amostradas aleatoriamente 300 propriedades e, dentro dessas, foi escolhido de forma aleatória um número pré-estabelecido de animais, dos quais foi obtida uma amostra de sangue. No total, foram amostrados 10.744 animais, provenientes de 900 propriedades. Em cada propriedade visitada aplicou-se um questionário epidemiológico para verificar o tipo de exploração e as práticas de criação e sanitárias que poderiam estar associadas ao risco de infecção pela doença. O protocolo de testes utilizado foi o da triagem com o teste do antígeno acidificado tamponado e a confirmação dos positivos com o teste do 2-mercaptoetanol. O rebanho foi considerado positivo quando pelo menos um animal foi reagente às duas provas sorológicas. No estrato 1, a prevalência foi de 7,7 por cento [4,7-10,7 por cento] para propriedades, e de 1,4 por cento [0,99-1,7 por cento] para animais. No estrato 2, foi de 19,5 por cento [15,0-24,0 por cento] para propriedades e de 2,6 por cento [2,0-3,1 por cento] para animais. No estrato 3, foi de 21,4 por cento [16,7-26,1] para propriedades e 4,3 por cento [3,7-5,0 por cento] para animais. A prevalência obtida para o Estado foi de 17,5 por cento [14,9-20,2 por cento] para propriedades e de 3,0 por cento [2,7-3,3 por cento] para animais. Os fatores de risco (odds ratio, OR) associados à condição de foco, segundo a análise multivariada, foram: compra de reprodutores a comerciantes de gado (OR = 2,06 [1,12-3,52]), ocorrência de abortos nos últimos 12 meses (OR = 5,83 [3,86-8,8]) e prática de vacinação contra brucelose (OR = 2,07 [1,38-3,09]). Tanto a ocorrência de aborto quanto a vacinação são, neste caso, consequência da presença de brucelose no rebanho.

A study to characterize the epidemiological status of brucellosis in the State of Goiás was carried out. The State was divided in three regions. Three hundred herds were randomly sampled in each region and a pre-established number of animals was sampled in each of these herds. A total of 10,744 serum samples from 900 herds were collected. In each herd, it was applied an epidemiological questionnaire focused on herd traits as well as husbandry and sanitary practices that could be associated with the risk of infection. The serum samples were screened for antibodies against Brucella spp. by the Rose-Bengal Test (RBT), and all positive sera were re-tested by the 2-Mercaptoethanol test (2-ME). The herd was considered positive if at least one animal was positive on both RBT and 2-ME tests. For region 1, the herd prevalence was 7.7 percent [4.7-10.7 percent] and the animal prevalence was 1.4 percent [0.99-1.7 percent]. For region 2, the herd prevalence was 19.5 percent [15.0-24.0 percent] and the animal prevalence was 2.6 percent [2.0-3.1 percent]. For region 3, the herd prevalence was 21.4 percent [16.8-26.1 percent] and the animal prevalence was 4.3 percent [3.7-5.0 percent]. For the whole state, the herd prevalence was 17.5 percent [14.9-20.2 percent] and the animal prevalence was 3.0 percent [2.7-3.3 percent]. The multivariate analysis identified the following risk factors (odds ratio, OR) associated with positive herds: purchase of breeding stock from cattle traders (OR = 2.06 [1.12-3.52]), occurrence of abortions over the last 12 months (OR = 5.83 [3.86-8.8]), and vaccination against brucellosis (OR = 2.07 [1.38-3.09]). Both the abortions and the vaccination are, in this case, a consequence of the herd being infected with brucellosis.

Situação epidemiológica da brucelose bovina no Estado de Minas Gerais / Epidemiological status of bovine brucellosis in the State of Minas Gerais, Brazil

Realizou-se um estudo para caracterizar a situação epidemiológica da brucelose bovina no Estado de Minas Gerais. O Estado foi estratificado em sete circuitos produtores. Em cada circuito foram amostradas aleatoriamente cerca de 300 propriedades e, dentro dessas, foi escolhido, de forma aleatória, um número pré-estabelecido de animais, dos quais foi obtida uma amostra de sangue. No total, foram amostrados 20.643 animais, provenientes de 2.204 propriedades. Em cada propriedade visitada aplicou-se um questionário epidemiológico para verificar o tipo de exploração e as práticas zootécnicas e sanitárias que poderiam estar associadas ao risco de infecção pela doença. O protocolo de testes utilizado foi o da triagem com o teste do antígeno acidificado tamponado e a confirmação dos positivos com o teste do 2-mercaptoetanol. O rebanho foi considerado positivo, se pelo menos um animal foi reagente às duas provas sorológicas. As prevalências de focos e de animais infectados do Estado foram de 6,0 por cento [5,0-7,1 por cento] e 1,1 por cento [0,78-1,4 por cento], respectivamente. Os resultados para os circuitos pecuários da prevalência de focos e de animais foram: circuito 1, 4,7 por cento [2,7-7,7 por cento] e 0,82 por cento [0,06-1,6 por cento]; circuito 2, 7,2 por cento [4,6-10,6 por cento] e 1,2 por cento [0,53-1,8 por cento]; circuito 3, 6,8 por cento [4,3-10,0 por cento] e 1,5 por cento [0,47-2,4 por cento]; circuito 4, 6,5 por cento [4,1-9,8 por cento] e 1,1 por cento [0,39-1,7 por cento]; circuito 5, 3,8 por cento [2,0-6,5 por cento] e 0,40 por cento [0,11-0,69 por cento]; circuito 6, 6,2 por cento [3,8-9,6 por cento] e 0,66 por cento [0,29-1,0 por cento]; circuito 7, 11,0 por cento [7,7-15,0 por cento] e 1,7 por cento [0,92-2,6 por cento], respectivamente. Os fatores de risco (odds ratio, OR) associados à condição de foco foram: compra de reprodutores (OR = 1,66 [1,13-2,44]), ocorrência de aborto nos últimos 12 meses (OR = 1,81 [1,26-2,60]) ...

A study to characterize the epidemiological status of brucellosis was carried out in the State of Minas Gerais. The State was divided in seven regions. Three hundred herds were randomly sampled in each region and a pre-established number of animals was sampled in each of these herds. A total of 20,643 serum samples from 2,204 herds were collected. In each herd, it was applied an epidemiological questionnaire focused on herd traits as well as husbandry and sanitary practices that could be associated with the risk of infection. The serum samples were screened for antibodies against Brucella spp. by the Rose-Bengal Test (RBT), and all positive sera were re-tested by the 2-mercaptoethanol test (2-ME). The herd was considered positive if at least one animal was positive on both RBT and 2-ME tests. The prevalence of infected herds and animals in the State were, respectively, 6.0 percent [5.0-7.1 percent] and 1.1 percent [0.78-1.4 percent]. In the productive regions, the prevalence of infected herds and animals were, respectively: regions 1, 4.7 percent [2.7-7.7 percent] and 0.82 percent [0.06-1.6 percent]; region 2, 7.2 percent [4.6-10.6 percent] and 1.2 percent [0.53-1.8 percent]; region 3, 6.8 percent [4.3-10.0 percent] and 1.5 percent [0.47-2.4 percent]; region 4, 6.5 percent [4.1-9.8 percent] and 1.1 percent [0.39-1.7 percent]; region 5, 3.8 percent [2.0-6.5 percent] and 0.40 percent [0.11-0.69 percent]; region 6, 6.2 percent [3.8-9.6 percent] and 0.66 percent [0.29-1.0 percent]; and region 7, 11.0 percent [7.7-15.0 percent] and 1.7 percent [0.92-2.6 percent]. The risk factors (odds ratio, OR) associated with positive herds were: purchase of breeding stock (OR = 1.66 [1.13-2.44]), occurrence of abortions over the last 12 months (OR = 1.81 [1.26-2.60]), and the presence of deer in the farm (OR = 1.56 [1.08-2.27]). Vaccination against brucellosis was a protective factor (OR = 0.38 [0.19-0.79]). It can be concluded that the compulsory vaccination ...

Situação epidemiológica da brucelose bovina no Estado do Mato Grosso do Sul / Epidemiological situation of bovine brucellosis in the State of Mato Grosso do Sul, Brazil

Realizou-se um estudo para caracterizar a situação epidemiológica da brucelose bovina no Estado de Mato Grosso do Sul. Foram definidos três estratos (regiões): Pantanal-corte, Planalto-corte e Planalto-leite, este último subdividido em Bolsão, Campo Grande e Dourados. Em cada estrato foram amostradas aleatoriamente propriedades e, dentro dessas, foi escolhido, de forma aleatória, um número pré-estabelecido de animais, dos quais foi obtida uma amostra de sangue. No total, foram amostrados 14.849 animais, provenientes de 1.004 propriedades. Em cada propriedade amostrada foi aplicado um questionário epidemiológico para verificar suas características e também para detectar transtornos reprodutivos que poderiam estar associados à infecção brucélica. O teste utilizado foi o do antígeno acidificado tamponado. O rebanho foi considerado positivo se pelo menos um animal foi reagente à prova sorológica. Para o Estado, a prevalência de focos foi de 41,5 por cento [36,5-44,7 por cento]. As prevalências de focos e de animais infectados por estrato foram, respectivamente, de: 59,0 por cento [52,8-64,9 por cento] e 12,6 por cento [9,1-17,2 por cento] para o estrato Pantanal-corte, e 40,6 por cento [35,8-45,5 por cento] e 4,5 por cento [2,1-9,0 por cento] para Planalto-corte. No estrato Planalto-leite, a prevalência de focos foi de 33,1 por cento [28,4-38,1 por cento]. Os fatores de risco (odds ratios, OR) associados à condição de foco foram: ter ≥500 vacas (OR = 2,46 [1,81-3,34]), ocorrência de bezerros fracos (OR = 1,20 [0,87-1,65]) e uso da inseminação artificial (OR = 0,71 [0,50-1,01]).

A study to characterize the epidemiological status of bovine brucellosis in the State of Mato Grosso do Sul was carried out. The State was divided in three regions: beef cattle Pantanal, beef cattle Plateau, and dairy cattle Plateau. Herds were randomly sampled in each region and a pre-established number of animals were sampled in each of these herds. A total of 14,849 serum samples from 1,004 herds were collected. In each herd, it was applied an epidemiological questionnaire focused on herd traits as well as clinical signs that could be associated with the brucellosis infection. The serum samples were tested for antibodies against Brucella spp. by the Rose-Bengal test. The herd was considered positive if at least one animal was positive. The prevalence of infected herds in the State was 41.5 percent [36.5-44.7 percent]. The prevalence of infected herds in the regions were, respectively: 40.6 percent [35.8-45.5 percent] for beef cattle Plateau, 59.0 percent [52.8-64.9 percent] for beef cattle Pantanal, and 33.1 percent [28.4-38.1 percent] for dairy cattle Plateau. The risk factors (odds ratio, OR) associated with the presence of the infection were: herd size larger than 500 cows (OR = 2.46 [1.81-3.34]), birth of weak calf (OR = 1.20 [0.87-1.65]), and use of artificial insemination (OR = 0.71 [0.50-1.01]).

Situação epidemiológica da brucelose bovina no Estado do Paraná / Epidemiological situation of bovine brucellosis in the State of Paraná, Brazil

Realizou-se um estudo para caracterizar a situação epidemiológica da brucelose bovina no Estado do Paraná. O Estado foi estratificado em sete circuitos produtores ou regiões. Em cada circuito foram amostradas aleatoriamente cerca de 300 propriedades e, dentro dessas, foi escolhido de forma aleatória um número pré-estabelecido de animais, dos quais foi obtida uma amostra de sangue. No total, foram amostrados 14.857 animais, provenientes de 2.098 propriedades. Em cada propriedade amostrada foi aplicado um questionário epidemiológico para verificar o tipo de exploração e as práticas zootécnicas e sanitárias que poderiam estar associadas ao risco de infecção pela doença. O protocolo de testes utilizado foi o da triagem com o teste do antígeno acidificado tamponado e o reteste dos positivos com o teste do 2-mercaptoetanol. O rebanho foi considerado positivo se pelo menos um animal foi reagente às duas provas sorológicas. Para o Estado, os resultados de prevalências de focos e de animais infectados foram, respectivamente, de 4,0 por cento [3,2-4,8 por cento] e 1,7 por cento [1,1-2,4 por cento]. Para os circuitos, a prevalência de focos e a de animais foram, respectivamente: circuito 1, 14,7 por cento [10,9-19,2 por cento] e 2,8 por cento [1,2-4,4 por cento]; circuito 2, 8,8 por cento [5,9-12,6 por cento] e 2,4 por cento [1,0-3,8 por cento]; circuito 3, 3,4 por cento [1,6-6,1 por cento] e 0,85 por cento [0,21-1,5 por cento]; circuito 4, 2,3 por cento [0,94-4,8 por cento] e 0,83 por cento [0,02-1,6 por cento]; circuito 5, 2,3 por cento [0,94-4,7 por cento] e 1,6 por cento [0,06-3,3 por cento]; circuito 6, 0,3 por cento [0-1,9 por cento] e 0,09 por cento [0-0,27 por cento]; circuito 7, 1,0 por cento [0,21-2,9 por cento] e 2,2 por cento [0-6,0 por cento]. Os fatores de risco (odds ratio, OR) associados à condição de foco foram: compra de reprodutores (OR= 2,20 [1,42-3,40]) e prática de aluguel de pasto (OR= 2,45 [1,54-3,90]).

A study to characterize the epidemiological situation of bovine brucellosis in the State of Paraná was carried out. In this study, the State was divided into seven regions. Three hundred herds were randomly sampled in each region and a pre-established number of animals were sampled in each of these herds. A total of 1,4857 serum samples from 2,098 herds were collected. In each herd, it was applied an epidemiological questionnaire regarding herd features and also husbandry and sanitary practices that could be associated with risk of infection. The serum samples were screened for antibodies against Brucella spp. by the Rose-Bengal test (RBT), and all RBT-positive sera were re-tested by the 2-mercaptoethanol test (2-ME). A herd was considered positive if at least one animal was positive on both RBT and 2-ME tests. The prevalences of infected herds and infected animals in Paraná State were 4.0 percent [3.2-4.8 percent] and 1.7 percent [1.1-2.4 percent], respectively. In the regions, the prevalences of infected herds and animals were: region 1, 14.7 percent [10.9-19.2 percent] and 2.8 percent [1.2-4.4 percent]; region 2, 8.8 percent [5.9-12.6 percent] and 2.4 percent [1.0-3.8 percent]; region 3, 3.4 percent [1.6-6.1 percent] and 0.85 percent [0.21-1.5 percent]; region 4, 2.3 percent [0.94-4.8 percent] and 0.83 percent [0.02-1.6 percent]; region 5, 2.3 percent [0.94-4.7 percent] and 1.7 percent [0.06-3.3 percent]; region 6, 0.34 percent [0-1.9 percent] and 0.09 percent [0-0.27 percent]; and region 7, 1.0 percent [0.21-2.9 percent] and 2.2 percent [0-6,0 percent]. The risck factors (odds ratio, OR) associated with the presence of the infection were: purchase of animals for breeding (OR= 2.20 [1.42-3.40]) and pasture rental practice (OR=2.45 [1.54-3.90]).

Situação epidemiológica da brucelose bovina no Estado do Rio de Janeiro / Epidemiological situation of bovine brucellosis in the State of Rio de Janeiro, Brazil

Realizou-se um estudo para caracterizar a situação epidemiológica da brucelose bovina no Estado do Rio de Janeiro. O Estado foi dividido em três circuitos produtores. Em cada circuito foram amostradas aleatoriamente cerca de 300 propriedades e, dentro dessas, foi escolhido, de forma aleatória, um número pré-estabelecido de animais, dos quais foi obtida uma amostra de sangue. No total foram amostrados 8239 animais, provenientes de 945 propriedades. Em cada propriedade amostrada foi aplicado um questionário epidemiológico para verificar o tipo de exploração e as práticas zootécnicas e sanitárias que poderiam estar associadas ao risco de infecção pela doença. O protocolo de testes utilizado foi o da triagem com o teste do antígeno acidificado tamponado e reteste dos positivos com o teste do 2-mercaptoetanol. O rebanho foi considerado positivo se pelo menos um animal foi reagente às duas provas sorológicas. Para o Estado, as prevalências de focos e de animais infectados foram, respectivamente, de 15,4 por cento [12,9-17,9 por cento] e de 4,1 por cento [2,8-5,3 por cento]. Para os circuitos, as prevalências de focos e de animais infectados foram, respectivamente: circuito 1, 13,8 por cento [10,2-18,2 por cento] e 3,0 por cento [1,9-4,1 por cento]; circuito 2, 15,7 por cento [11,9-20,2 por cento] e 2,3 por cento [1,4-3,2 por cento]; circuito 3, 19,6 por cento [15,4-24,4 por cento] e 9,3 por cento [4,5-14,1 por cento]. Os fatores de risco (odds ratio, OR) associados à condição de foco foram: ter mais que 30 fêmeas com idade de 24 meses ou acima (OR=2,33 [1,51-3,07]), compra de reprodutores (OR= 1,95 [1,13-2,45]) e prática de aluguel de pasto (OR= 1,74 [1,03-2,74]).

A study to characterize the epidemiological status of bovine brucellosis in the State of Rio de Janeiro was carried out. The State was divided in three regions. Three hundred herds were randomly sampled in each region and a pre-established number of animals were sampled in each herd. A total of 8,239 serum samples from 945 herds were collected. In each herd, it was applied an epidemiological questionnaire focused on herd traits as well as husbandry and sanitary practices that could be associated with the risk of infection. The serum samples were screened for antibodies against Brucella spp. by the Rose-Bengal Test (RBT), and all positive sera were re-tested by the 2-mercaptoethanol test (2-ME). The herd was considered positive if at least one animal was positive on both RBT and 2-ME tests. The prevalences of infected herds and animals in the State were, respectively: 15.4 percent [12.9-17.9 percent] and 4.1 percent [2.8-5.3 percent]. The prevalences of infected herds and animals in the regions were, respectively: region 1, 13.8 percent [10.2-18.2 percent] and 3.0 percent [1.9-4.1 percent]; region 2, 15.7 percent [11.9-20.2 percent] and 2.3 percent [1.4-3.2 percent]; and region 3, 19.6 percent [15.4-24.4 percent] and 9.3 percent [4.5-14.1 percent]. The risk factors (odds ratio, OR) associated with the presence of the infection were: herd size larger than 30 cows (OR=2.33 [1.51-3.07]), purchase of animals for breeding (OR= 1.95 [1.13-2.45), and pasture rental practice (R= 1.74 [1.03-2.74]).

Situação epidemiológica da brucelose bovina no Estado de Rondônia / Epidemiological situation of bovine brucellosis in the State of Rondônia, Brazil

Realizou-se um estudo para caracterizar a situação epidemiológica da doença no Estado de Rondônia. O Estado foi estratificado em três circuitos produtores. Em cada circuito produtor foram amostradas aleatoriamente cerca de 300 propriedades e, dentro dessas, foi escolhido, de forma aleatória, um número pré-estabelecido de animais, dos quais foi obtida uma amostra de sangue. No total, foram amostrados 9.717 animais, provenientes de 927 propriedades. Em cada propriedade amostrada foi aplicado um questionário epidemiológico para verificar o tipo de exploração e as práticas zootécnicas e sanitárias que poderiam estar associadas ao risco de infecção pela doença. O protocolo de testes utilizado foi o da triagem com o teste do antígeno acidificado tamponado e o reteste dos positivos com o teste do 2-mercaptoetanol. O rebanho foi considerado positivo, se pelo menos um animal foi reagente às duas provas sorológicas. As prevalências de focos e de animais infectados do Estado foram de 35,2 por cento [32,1-38,4 por cento] e 6,2 por cento [4,9-7,6 por cento], respectivamente. Os resultados para os circuitos pecuários foram: circuito 1, 41,9 por cento [36,3-47,6 por cento] e 8,3 por cento [5,9-10,8 por cento]; circuito 2, 31,7 por cento [26,5-37,2 por cento] e 5,9 por cento [4,3-7,6 por cento]; circuito 3, 31,9 por cento [26,7-37,4 por cento] e 4,6 por cento [2,5-6,6 por cento]. Os fatores de risco (odds ratio, OR) associados à condição de foco foram: histórico de aborto (OR= 1,42 [1,04-1,95]) e exploração de corte (OR= 1,75 [1,30-2,38]).

A study to characterize the brucellosis epidemiological situation in the State of Rondônia was carried out. The State was divided into three regions. Three hundred herds were randomly sampled in each region. A pre-established number of animals were sampled in each of these herds. From 927 herds and 9,717 serum samples were collected. In each herd, it was applied an epidemiological questionnaire regarding herd features and also husbandry and sanitary practices that could be associated with risk of infection. The serum samples were screened for antibodies to Brucella spp. by the Rose-Bengal Test (RBT), and all RBT-positive sera were re-tested by the 2-mercaptoethanol test (2-ME). The herd was considered positive if at least one animal was positive on both RBT and 2-ME tests. The prevalences of infected herds and animals in Rondônia State were 35.2 percent [32.1-38.4 percent] and 6.2 percent [4.9-7.6 percent], respectively. In the regions, the prevalences of infected herds and animals were, respectively: region 1, 41.9 percent [36.3-47.6 percent] and 8.3 percent [5.9-10.8 percent]; region 2, 31.7 percent [26.5-37.2 percent] and 5.9 percent [4.3-7.6 percent]; and region 3, 31.9 percent [26.7-37.4 percent] and 4.6 percent [2.5-6.6 percent]. The risk factors (odds ratio, OR) associated with the presence of the infection were: recent history of abortion (OR= 1.42 [1.04-1.95]) and beef herd (OR=1.75 [1.30-2.38]).

Situação epidemiológica da brucelose bovina no Estado do Rio Grande do Sul / Epidemiological situation of bovine brucellosis in the State of Rio Grande do Sul, Brazil

Realizou-se um estudo para caracterizar a situação epidemiológica da brucelose bovina. O Estado foi dividido em sete regiões. Em cada região foram amostradas aleatoriamente cerca de 300 propriedades, e dentro dessas foi escolhido de forma aleatória um número pré-estabelecido de animais, dos quais foi obtida uma amostra de sangue. No total foram amostrados 16.072 animais, provenientes de 1.957 propriedades. Em cada propriedade amostrada foi aplicado um questionário epidemiológico para verificar o tipo de exploração e as práticas zootécnicas e sanitárias que poderiam estar associadas ao risco de infecção pela doença. O protocolo de testes utilizado foi o da triagem com o teste do antígeno acidificado tamponado e o reteste dos positivos com o teste do 2-mercaptoetanol. O rebanho foi considerado positivo se pelo menos um animal foi reagente às duas provas sorológicas. Para o Estado, as prevalências de focos e de animais infectados foram, respectivamente, 2,1 por cento [1,5-2,6 por cento] e 1,0 por cento [0,60-1,4 por cento]. Para os circuitos, a prevalência de focos e a de animais foram, respectivamente: circuito 1, 3,1 por cento [1,4-5,7 por cento] e 0,95 por cento [0,0-2,0 por cento]; circuito 2, 7,7 por cento [4,9-11,3 por cento] e 1,0 por cento [0,40-1,7 por cento]; circuito 3, 5,7 por cento [3,4-8,8 por cento] e 2,1 por cento [0,41-3,8 por cento]; circuito 4, 0,66 por cento [0,08-2,4 por cento] e 0,66 por cento [0,0-1,8 por cento]; circuito 5, 0,66 por cento [0,08-2,4 por cento] e 0,05 por cento [0,0-0,13 por cento]; circuito 6, 0,0 por cento [0,0-1,3 por cento] e 0,0 por cento [0,0-0,25 por cento]; circuito 7, 5,4 por cento [2,5-10,1 por cento] e 2,9 por cento [0,49-5,3 por cento]. Os fatores de risco (odds ratio, OR) associados à condição de foco foram: exploração de corte (OR= 4,27 [1,82-10,01]) e histórico de aborto (OR= 3,27, [1,71-6,25]).

A study to characterize the epidemiological status of bovine brucellosis was carried out in the State of Rio Grande do Sul. The State was divided in seven regions. Three hundred herds were randomly sampled in each region and a pre-established number of animals were sampled in each of these herds. A total of 16,072 serum samples from 1,957 herds, were collected. In each herd, it was applied an epidemiological questionnaire focused on herd traits as well as husbandry and sanitary practices that could be associated with the risk of infection. The serum samples were screened for antibodies against Brucella spp. by the Rose-Bengal Test and all positive sera were re-tested by the 2-mercaptoethanol test. The herd was considered positive if at least one animal was positive on both tests. The prevalences of infected herds and animals in the State were, respectively 2.1 percent [1.5-2.6 percent] and 1.0 percent [0.60-1.4 percent]. In the regions, the prevalences of infected herds and animals were, respectively: region 1, 3.1 percent [1.4-5.7 percent] and 0.95 percent [0.0-2.0 percent]; region 2, 7.7 percent [4.9-11.3 percent] and 1.0 percent [0.40-1.7 percent]; region 3, 5.7 percent [3.4-8.8 percent] and 2.1 percent [0.41-3.8 percent]; region 4, 0.66 percent [0.08-2.4 percent] and 0.66 percent [0.0-1.8 percent]; region 5, 0.66 percent [0.08-2.4 percent] and 0.05 percent [0.0-0.13 percent]; region 6, 0.0 percent [0.0-1.3 percent] and 0.0 percent [0.0-0.25 percent]; and region 7, 5.4 percent [2.5-10.1 percent] and 2.9 percent [0.49-5.3 percent]. The risk factors (odds ratio, OR) associated with the presence of infection were: beef herd (OR= 4.27 [1.82-10.01]) and recent history of abortion (OR= 3.27-1.71-6.25]).

Situação epidemiológica da brucelose bovina no Estado de Santa Catarina / Epidemiological situation of bovine brucellosis in the State of Santa Catarina, Brazil

Realizou-se um estudo para caracterizar a situação epidemiológica da brucelose bovina no Estado de Santa Catarina. O Estado foi estratificado em cinco circuitos produtores. Em cada circuito produtor foram amostradas aleatoriamente cerca de 300 propriedades e, dentro dessas, foi escolhido, de forma aleatória, um número pré-estabelecido de animais, dos quais foi obtida uma amostra de sangue. No total foram amostrados 7801 animais, provenientes de 1586 propriedades. O protocolo de testes utilizado foi o da triagem com o teste do antígeno acidificado tamponado e o reteste dos positivos com o do 2-mercaptoetanol. O rebanho foi considerado positivo se pelo menos um animal foi reagente às duas provas sorológicas. As prevalências de focos e de animais infectados no Estado foram de 0,32 por cento [0,10-0,69 por cento] e 0,06 por cento [0,0-0,17 por cento], respectivamente. A prevalência de focos nos circuitos pecuários foram: circuito 1, 0,33 por cento [0,0-0,99 por cento]; circuito 2, 0,33 por cento [0,0-1,0 por cento]; circuito 3, 0,25 por cento [0,0-0,75 por cento]; circuito 4, 0,66 por cento [0,08-1,84 por cento] e circuito 5, 0,33 por cento [0,0-1,0 por cento].

A study to characterize the brucellosis epidemiological situation in the State of Santa Catarina was carried out. The State was divided into five regions. Three hundred herds were randomly sampled in each region and a pre-established number of animals were sampled in each of these herds. A total of 7,801 serum samples from 1,586 herds were collected. In each herd, it was applied an epidemiological questionnaire regarding herd features and also husbandry and sanitary practices that could be associated with risk of infection. The serum samples were screened for antibodies to Brucella spp. by the Rose-Bengal Test (RBT), and all RBT-positive sera re-tested by the 2-mercaptoethanol test (2-ME). The herd was considered positive if at least one animal was positive on both RBT and 2-ME tests. The prevalences of infected herds and animals in Santa Catarina State were, respectively: 0.32 percent [0.10-0.69 percent] and 0.06 percent [0.0-0.17 percent]. The prevalence of infected herds in the regions were: region 1, 0.33 percent [0.0-0.99 percent]; region 2, 0.33 percent [0.0-1.0 percent]; region 3, 0.25 percent [0.0-0.75 percent]; region 4, 0.66 percent [0.08-1.84 percent]; and region 5, 0.33 percent [0.0-1.00 percent].